In a process for purifying carboxylic esters such as ethyl formate, a carboxylic ester to be purified is distilled in the presence of an extractant, preferably by (a) allowing vapor of the carboxylic ester to be purified to ascend in a distillation column; (b) conveying the extractant in countercurrent to the vapor in an extractive distillation column; (c) taking off pure carboxylic ester above the extractive distillation zone. The extractant is, for example, selected from among diols, polyols, open-chain or cyclic amides.